Recently, regulation has been deepened on waste gas in automobiles due to the exhaustion of fossil fuels and environmental-related problems. As a result, the reduction of weight in automobile bodies to increase automobile fuel efficiency has come to the fore.
Various kinds of high-strength steel sheets have been developed to accomplish the reduction in weight of automobile bodies. As the strength of the steel sheets increases, however, the steel sheets exhibit low ductility. As a result, the use of the steel sheets to be formed as automobile parts is limited.
Much research has been carried out to epochally solve the reduction in ductility of the high-strength steel sheets. As a result, technologies have been proposed for adding 7 to 35 weight % of Mn to a steel, such that the twin deformation of the steel is maintained when the steel is plastically deformed, thereby considerably improving the ductility of the steel while maintaining high strength of the steel (WO93/013233, JP1992-259325, WO99/001585, and WO02/101109).
Meanwhile, Mn is an element exhibiting high ionization tendency. For this reason, a steel having a high Mn content corrodes more rapidly than general steels.
In order that a steel having a high Mn content may be applied to automobiles, therefore, it is necessary to treat the steel such that the steel has high corrosion resistance.
However, development has not taken place on an optimum coating layer and a hot-dip coating process for providing a high-manganese steel containing approximately 5 to 35 weight % of Mn with high corrosion resistance.
It is an aspect of the present invention to provide a high-manganese hot-dip coated steel sheet exhibiting high corrosion resistance and high workability as well as high ductility and high strength.
It is another aspect of the present invention to provide a method of hot-dip coating a high-manganese steel sheet to manufacture a high-manganese hot-dip coated steel sheet exhibiting high corrosion resistance and high workability as well as high ductility and high strength.